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At least 199 records · Page 11Linked to original sources
PubMed2004

Bisphosphonate treatment affects trabecular bone apparent modulus through micro-architecture rather than matrix properties.

Bisphosphonates are emerging as an important treatment for osteoporosis. But whether the reduced fracture risk associated with bisphosphonate treatment is due to increased bone mass, improved trabecular architecture and/or increased secondary mineralization of the calcified matrix remains unclear. We examined the effects of bisphosphonates on both the trabecular architecture and matrix properties of canine trabecular bone. Thirty-six beagles were divided into a control group and two treatment groups, one receiving risedronate and the other alendronate at 5-6 times the clinical dose for osteoporosis treatment. After one year, the dogs were killed, and samples from the first lumbar vertebrae were examined using a combination of micro-computed tomography, finite element modeling, and mechanical testing. By combining these methods, we examined the treatment effects on the calcified matrix and trabecular architecture independently. Conventional histomorphometry and microdamage data were obtained from the second and third lumbar vertebrae of the same dogs [Bone 28 (2001) 524]. Bisphosphonate treatment resulted in an increased apparent Young's modulus, decreased bone turnover, increased calcified matrix density, and increased microdamage. We could not detect any change in the effective Young's modulus of the calcified matrix in the bisphosphonate treated groups. The observed increase in apparent Young's modulus was due to increased bone mass and altered trabecular architecture rather than changes in the calcified matrix modulus. We hypothesize that the expected increase in the Young's modulus of the calcified matrix due to the increased calcified matrix density was counteracted by the accumulation of microdamage.

Alendronate↗
PubMed2026

Shared genetic architecture between major depression and intrinsic brain functional connectome organization.

BACKGROUND: Major depression (MD) is increasingly understood as a disorder characterized by widespread abnormalities in intrinsic brain functional network organization. Although both MD and brain functional connectome architecture are highly heritable, the genetic architecture underlying their relationship remains poorly characterized. METHODS: We integrated genome-wide association studies of MD with 191 ICA-based resting-state functional connectome traits to investigate their shared genetic architecture. These traits captured intrinsic connectome organization across amplitude, functional connectivity, and global connectivity domains. Cross-trait genetic analyses were used to assess pleiotropic overlap between traits. Locus-level and gene-based analyses integrating multi-omics evidence were performed to characterize the biological relevance of shared genetic signals. RESULTS: We identified significant genetic overlap between MD and 148 of 191 brain functional connectome traits. Cross-trait analyses revealed widespread shared genetic signals organized into 627 genomic loci across amplitude, functional connectivity, and global connectivity measures. Among these, 193 loci showed evidence consistent with shared causal variants based on colocalization analyses. Gene-level integration mapped these loci to 1459 protein-coding genes (390 unique genes). Multi-layer prioritization identified 17 high-confidence genes supported by convergent genomic, transcriptomic, and proteomic evidence, with enrichment in neurodevelopmental and lipid-related metabolism pathways. CONCLUSIONS: This study provides a multi-scale characterization of the shared genetic architecture between MD and intrinsic brain functional connectome organization, revealing that shared genetic signals between MD and brain functional systems are distributed across multiple functional levels and converge at the molecular level.

Connectome↗
PubMedDate not supplied

Ground and on-orbit command and data handling architectures for the Active Rack Isolation System microgravity flight experiment.

The Active Rack Isolation System [ARIS] International Space Station [ISS] Characterization Experiment, or ARIS-ICE for short, is a long duration microgravity characterization experiment aboard the ISS. The objective of the experiment is to fully characterize active microgravity performance of the first ARIS rack deployed on the ISS. Efficient ground and on-orbit command and data handling [C&DH] segments are the crux in achieving the challenging objectives of the mission. The objective of the paper is to provide an overview of the C&DH architectures developed for ARIS-ICE, with the view that these architectures may serve as a model for future ISS microgravity payloads. Both ground and on-orbit segments, and their interaction with corresponding ISS C&DH systems are presented. The heart of the on-orbit segment is the ARIS-ICE Payload On-orbit Processor, ARIS-ICE POP for short. The POP manages communication with the ISS C&DH system and other ISS subsystems and payloads, enables automation of test/data collection sequences, and provides a wide range of utilities such as efficient file downlinks/uplinks, data post-processing, data compression and data storage. The hardware and software architecture of the POP is presented and it is shown that the built-in functionality helps to dramatically streamline the efficiency of on-orbit operations. The ground segment has at its heart special ARIS-ICE Ground Support Equipment [GSE] software developed for the experiment. The software enables efficient command and file uplinks, and reconstruction and display of science telemetry packets. The GSE software architecture is discussed along with its interactions with ISS ground C&DH elements. A test sequence example is used to demonstrate the interplay between the ground and on-orbit segments.

Acceleration↗
PubMed2006

QTL mapping for plant architecture traits in upland cotton using RILs and SSR markers.

Xiangzamian 2 (XZM2) is the most widely cultivated cotton hybrid in China. By crossing two parents Zhongmiansuo12 and 8891 and upon subsequent selfings, we got F8 and F9 populations having 180 recombinant inbred lines. Ten plant architecture traits were investigated in two years with this population. A genetic map was constructed mainly with SSR markers. Quantitative trait loci (QTL) conditioning plant architecture traits were determined at the single-locus and double-locus levels. The results showed that epistastic effects as well as additive effects of QTL played an important role as the genetic basis of cotton plant architecture. The QTL detected in our research might provide new information on improving plant architecture traits. The polymorphism of molecular markers between ZMS12 and 8891 were quite limited, while significant differences between their phenotypes were found and the hybrid XZM2 expressed high heterosis in yield. All these could be partly explained by the effect of epistatic QTL.

Breeding↗
PubMedDate not supplied

The standard 'Healthcare Information Systems Architecture' and the DHE middleware.

The integration and evolution of existing systems represents one of the most urgent priorities of health care information systems in order to allow the whole organisation to meet the increasing clinical organisational and managerial needs. This paper discusses how an open architecture, based on the introduction of a middleware of common health care-specific services not only reduces the effort necessary for allowing existing systems to interwork, but also automatically establishes a functional and information basis common to the whole organisation, on top of which also new applications can be rapidly developed, natively integrated with the rest of the system. Such architecture has been already formalised through the European standard, defined by the CEN/TC251 prENV 12967-1 'Architecture for Health care Information Systems' (CEN prENV 12967-1 'Health care Information Systems Architecture'). Thanks to the availability of industrial products conforming to the standard, the effectiveness and the validity of this approach has been already demonstrated in practice. For example, through the Hansa collaboration hospitals and industries from countries of the Western and Eastern Europe, as well as of the Middle East use the same industrial middleware (i.e. 'The DHE middleware-Information view'-SPRI, 1998, 'The DHE middleware-Functional view'-SPRI, 1998) for integrating existing systems as well as for developing new applications.

Computer Communication Networks↗
PubMed2003

Sleep architecture in normal Caucasian and Hispanic children aged 6-11 years recorded during unattended home polysomnography: experience from the Tucson Children's Assessment of Sleep Apnea Study (TuCASA).

OBJECTIVE: To obtain normative sleep architecture data from unattended home polysomnography in Caucasian and Hispanic children aged 6-11 years. DESIGN AND SUBJECTS: Unattended home polysomnography was performed on a single night in Caucasian and Hispanic children aged 6-11 years as part of the Tucson Children's Assessment of Sleep Apnea Study (TuCASA), a cohort study designed to examine the prevalence and correlates of sleep disordered breathing. A subset of 42 children enrolled in TuCASA who had no symptoms of any sleep disorder and had polysomnograms without technical recording problems. RESULTS: Sleep architecture in preadolescent Caucasian and Hispanic children was not different between boys and girls. However, total sleep time (TST), sleep efficiency (SLE) and time spent in REM sleep declined with increasing age. In addition, the number of sleep to wake stage shifts was slightly higher in younger children. Hispanic children had less Stage 3/4 sleep (18+/-1 vs. 22+/-1%, P</=0.02) and correspondingly more Stage 2 sleep (55+/-2 vs. 50.0+/-1%, P</=0.02) than their Caucasian counterparts. CONCLUSIONS: Using unattended home polysomnography, indices of sleep duration and architecture are not different between preadolescent boys and girls. However, with increasing age, TST and SLE decreased. In addition, there are differences in sleep architecture between Caucasians and Hispanics, which may be an important consideration in the evaluation of children with sleep disorders.

Child↗
PubMed2000

Trabecular architecture in women and men of similar bone mass with and without vertebral fracture: I. Two-dimensional histology.

While osteoporosis is characterized by a low bone mass there is a well-recognized overlap in bone mineral density (BMD) measurements between groups of subjects with and without vertebral fracture. To investigate whether differences in trabecular architecture may contribute to the presence or absence of fractures independent of the bone mass, fracture and nonfracture groups matched for age, gender, and BMD were assembled. Transiliac biopsies and corresponding lumbar spine BMD measurements from 31 women and 16 men with vertebral fracture were compared with those from 22 women and 11 men without fracture. Lumbar BMD (L1-4) was measured using a Hologic 2000 densitometer. The lumbar BMD was similar in women with and without fracture (0.63 g/cm(3) +/- 0.10 SD and 0.71 g/cm(3) +/- 0.17 SD, n.s.) and in men with and without fracture (0.72 g/cm(3) +/- 0.12 SD and 0.76 g/cm(3) +/- 0.17 SD, n.s.). Undecalcified iliac crest biopsy sections, 8 microm thick, were analyzed for remodeling variables and trabecular architecture using OsteoMeasure and TAS image analysis systems. No significant difference was found in either gender between fracture and nonfracture groups in percent bone volume (mean 10% in all groups), or in the wide range of remodeling and architectural variables measured, including the trabecular width, number, and separation, mean trabecular plate density and fractal dimension, as well as several indirect indices of connectivity including the node:terminus ratio, marrow star volume, and trabecular pattern factor. On the basis of this evidence it was concluded that there is no difference in the trabecular architecture between patients with crush fracture and controls when account is taken of bone mass. This suggests that microanatomical disruption is a predictable intrinsic feature of bone loss. However, there remains the possibility that the two-dimensional character of the structural deterioration measured indirectly is not sufficiently sensitive for the complex cancellous system. This is considered further in part II.

Adult↗
PubMed1998

Effect of mechanical set point of bone cells on mechanical control of trabecular bone architecture.

The architecture of trabecular bone is thought to be controlled by mechanosensitive bone cells, where hormones provide a background for their responses to mechanical signals. It has been suggested that, in osteoporosis, this response is hampered by changed hormonal levels, thereby increasing the mechanical set point of the cells, which would lead to bone loss. We have investigated if a temporary increase of the mechanical set point causes deterioration of trabecular bone architecture, such as seen in osteoporosis. Furthermore, the effects of a changed loading pattern were investigated for the same reason. For this purpose, we used a computer simulation model, which was based on the regulation of bone architecture by mechanosensitive osteocytes. It was found that a temporary shift of the mechanical set point causes no lasting changes in architecture. Although an increase of the mechanical set point induces bone loss, the mechanism of bone loss (trabecular thinning) differs from what is observed in osteoporosis (loss of whole trabeculae). Hence, a change of the mechanical set point alone cannot explain bone loss as seen in osteoporosis. On the other hand, the removal of load components in a particular direction resulted in irreversible loss of whole trabeculae. These results indicate that such temporary changes in loading patterns could be important risk factors for osteoporosis.

Adult↗
PubMed2001

The generality of architectural isomerism in designer inclusion frameworks.

We describe herein new structural isomers of a lamellar host system based on organodisulfonate "pillars" that connect opposing hydrogen-bonded sheets, consisting of topologically complementary guanidinium (G) ions and sulfonate (S) groups, to generate inclusion cavities between the sheets. These new isomers-zigzag brick, double brick, V-brick, and crisscross bilayer-expand significantly on our earlier report of architectural isomerism displayed by the discrete bilayer and simple brick forms. We demonstrate here that the discrete bilayer-simple brick isomerism, which was limited to several host-guest combinations based on the G(2)(4,4'-biphenyldisulfonate) host and one pair of compounds based on the G(2)(2,6-naphthalenedisulfonate), can be generalized to other organodisulfonate pillars. Furthermore, in many cases the selectivity toward the different framework isomers reflects a rather systematic templating role of the guest molecules and host-guest recognition during assembly of the lattice. We also describe a convenient approach to identifying and classifying the innumerable possible host architectures based upon the pillar projection topologies for the GS sheets and the intersheet connectivities. The discovery of these new architectures reveals a structural versatility for this class of materials that exceeds initial expectations and observations. Each topology produces different connectivities between the sheets in the third dimension that endows each framework isomer with uniquely shaped and sized inclusion cavities, enabling this host system to conform readily to different guests. The unlimited number of architectures available, combined with the inherent conformational softness and structural tunability of these host lattices, suggests a near universality for the GS system with respect to guest inclusion.

Journal Article↗
PubMed2002

The effect of macromolecular architecture in nanomaterials: a comparison of site isolation in porphyrin core dendrimers and their isomeric linear analogues.

The influence of macromolecular architecture on the physical properties of polymeric materials has been studied by comparing poly(benzyl ether) dendrons with their exact linear analogues. The results clearly confirm the anticipation that dendrimers are unique when compared to other architectures. Physical properties, from hydrodynamic volume to crystallinity, were shown to be different, and in a comparative study of core encapsulation in macromolecules of different architecture, energy transduction from the polymer backbone to a porphyrin core was shown to be different for dendrimers as compared to that of isomeric four- or eight-arm star polymers. Fluorescence excitation revealed strong, morphology dependent intramolecular energy transfer in the three macromolecular isomers investigated. Even at high generations, the dendrimers exhibited the most efficient energy transfer, thereby indicating that the dendritic architecture affords superior site isolation to the central porphyrin it surrounds.

Journal Article↗
PubMed2002

Influencing receptor-ligand binding mechanisms with multivalent ligand architecture.

Multivalent ligands can function as inhibitors or effectors of biological processes. Potent inhibitory activity can arise from the high functional affinities of multivalent ligand-receptor interactions. Effector functions, however, are influenced not only by apparent affinities but also by alternate factors, including the ability of a ligand to cluster receptors. Little is known about the molecular features of a multivalent ligand that determine whether it will function as an inhibitor or effector. We envisioned that, by altering multivalent ligand architecture, ligands with preferences for different binding mechanisms would be generated. To this end, a series of 28 ligands possessing structural diversity was synthesized. This series provides the means to explore the effects of ligand architecture on the inhibition and clustering of a model protein, the lectin concanavalin A (Con A). The structural parameters that were varied include scaffold shape, size, valency, and density of binding elements. We found that ligands with certain architectures are effective inhibitors, but others mediate receptor clustering. Specifically, high molecular weight, polydisperse polyvalent ligands are effective inhibitors of Con A binding, whereas linear oligomeric ligands generated by the ring-opening metathesis polymerization have structural properties that favor clustering. The shape of a multivalent ligand also influences specific aspects of receptor clustering. These include the rate at which the receptor is clustered, the number of receptors in the clusters, and the average interreceptor distance. Our results indicate that the architecture of a multivalent ligand is a key parameter in determining its activity as an inhibitor or effector. Diversity-oriented syntheses of multivalent ligands coupled with effective assays that can be used to compare the contributions of different binding parameters may afford ligands that function by specific mechanisms.

Chemical Precipitation↗
PubMed2006

Fabrication of copper hydroxyphosphate with complex architectures.

Copper hydroxyphosphate [Cu(2)(OH)PO(4)] with complex architectures has been synthesized through a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. Powder X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectrometry are used to characterize various properties of the obtained samples. Single-crystals, twinned-crystals, and various novel architectures of copper hydroxyphosphate can be constructed through a careful control of synthetic parameters, such as the molar ratio of initial reagents, reagent concentration, reaction time, and temperature. On the basis of structure and chemical bond analysis, copper hydroxyphosphate crystals tend to grow along the c-axis and have a rotation twinned-crystal growth habit, which is essential for the formation of various complex architectures. The current approach provides a facile strategy to synthesize copper hydroxyphosphate crystals with unique morphologies and complex architectures, which may be applicable to the synthesis of other inorganic materials.

Journal Article↗
PubMed2003

Is there an optimal root architecture for nitrate capture in leaching environments?

Little is known about root architectural attributes that aid the capture of nitrate from coarse-textured soil profiles of high leaching potential. In this study, a range of root architectures from the herringbone to the dichotomous structure were simulated, and their capacity to take up nitrate leaching through a sandy profile was recorded. All root systems had equal total volume at each point in time, and so were considered cost equivalent. These simulations showed that the root architecture likely to maximize nitrate capture from sandy soils (under the Mediterranean rainfall pattern experienced in Western Australia) is one that quickly produces a high density of roots in the top-soil early in the season, thereby reducing total nitrate leached with opening season rains, but also has vigorous taproot growth, enabling access to deep-stored water and leached nitrate later in the season. This is the first published, spatially explicit attempt to assess the ability of different root architectures equivalent in cost, to capture nitrate from a spatially and temporally heterogeneous soil environment.

Journal Article↗
PubMed2001

Comparing human skeletal muscle architectural parameters of cadavers with in vivo ultrasonographic measurements.

The purpose of this study was to document and compare the architectural parameters (fibre bundle length, angle of pennation) of human skeletal muscle in cadaveric specimens and live subjects. The medial (MG) and lateral (LG) gastrocnemius, and posterior (PS) and anterior (AS) soleus were examined bilaterally in 5 cadavers (mean age 72.6, range 65-83 y) and 9 live subjects (mean age 76.3, range 70-92 y). Data were obtained from direct measurement of cadaveric specimens and from ultrasonographic scans of the live subjects. In cadaveric muscle, fibre bundles were isolated; their length was measured in millimetres and pennation angles were recorded in degrees. In live muscle, similar measurements were taken from ultrasonographic scans of relaxed and contracted muscle. For the scans of relaxed muscle, subjects were positioned prone with the foot at a 90 degrees angle to the leg, and for scans of contracted muscle, subjects were asked to sustain full plantarflexion during the scanning process. Fibre bundle length and angle of pennation were compared at matched locations in both groups. It was found that the relationship between cadaveric and in vivo values for fibre length and angle of pennation varied between muscle parts. The cadaveric architectural parameters did not tend to lie consistently towards either extreme of relaxation or contraction. Rather, within MG, PS and AS, cadaveric fibre bundle lengths lay between those for relaxed and contracted in vivo muscle. Similarly both the anterior and posterior cadaveric fibre angles of pennation lay between the in vivo values within LG and PS. In summary, architectural characteristics of cadaveric muscle differ from both relaxed and contracted in vivo muscle. Therefore, when developing models of skeletal muscle based on cadaveric studies, the architectural differences between live and cadaveric tissue should be taken into consideration.

Aged↗
PubMed1990

Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high-resolution optical imaging of intrinsic signals.

We have shown previously the existence of small, activity-dependent changes in intrinsic optical properties of cortex that are useful for optical imaging of cortical functional architecture. In this study we introduce a higher resolution optical imaging system that offers spatial and temporal resolution exceeding that achieved by most alternative imaging techniques for imaging cortical functional architecture or for monitoring local changes in cerebral blood volume or oxygen saturation. In addition, we investigated the mechanisms responsible for the activity-dependent intrinsic signals evoked by sensory stimuli, and studied their origins and wavelength dependence. These studies enabled high-resolution visualization of cortical functional architecture at wavelengths ranging from 480 to 940 nm. With the use of near-infrared illumination it was possible to image cortical functional architecture through the intact dura or even through a thinned skull. In addition, the same imaging technique proved useful for imaging and discriminating sensory-evoked, activity-dependent changes in local blood volume and oxygen saturation (oxygen delivery). Illumination at 570 nm allowed imaging of activity-dependent blood volume increases, whereas at 600-630 nm, the predominant signal probably originated from activity-dependent oxygen delivery from capillaries. The onset of oxygen delivery started prior to the blood volume increase. Thus, optical imaging based on intrinsic signals is a minimally invasive procedure for monitoring short- and long-term changes in cerebral activity.

Animals↗
PubMed2006

Acute inflammation and loss of retinal architecture and function during experimental Bacillus endophthalmitis.

Rapid vision loss and explosive inflammation are devastating consequences of Bacillus endophthalmitis that have not been well defined. We therefore analyzed the evolution of intraocular inflammation and loss of retinal architecture and function during experimental Bacillus endophthalmitis. Mice were intravitreally injected with 100 CFU of B. cereus, and eyes were analyzed for bacterial growth, retinal function, architectural changes and retinal cellular stress, inflammatory cytokines, and infiltrating cells. Retinal electrophysiologic and structural changes began as early as 4 to 6 hr postinfection. Significant declines in retinal function paralleled the loss of retinal architecture. Glial fibrillary acidic protein (GFAP) was detected in retina, indicating potential stress. Polymorphonuclear leukocyte (PMN) infiltration into the vitreous began as early as 4 hr postinfection, coinciding with a significant increase in TNF-alpha in the eye. These results indicated that acute inflammation and detrimental architectural and electrophysiologic changes in the retina began earlier than once thought, suggesting that therapeutic intervention should be given at the earliest possible time to avoid vision loss during Bacillus endophthalmitis.

Acute Disease↗
PubMed2006

Manipulation of bee behavior by inflorescence architecture and its consequences for plant mating.

Angiosperms display flowers in many three-dimensional arrangements, but the functional significance of this diversity is largely unknown. We examined influences of inflorescence architecture on pollination and mating by quantifying the responses of bumblebees to three architectures and then using these observations as the basis of a model that simulated pollen dispersal. On artificial panicles, racemes, and umbels, each with 12 identical flowers, bees visited one more flower, on average, on umbels than on panicles (with racemes being intermediate). In contrast to this weak response, the consistency of foraging paths among flowers differed strongly among architectures (raceme > panicle > umbel). The simulation model revealed limited differences in self-pollination and pollen export among the three inflorescence designs when all flowers presented and received pollen, because mating differences depended on only the number of flowers visited. In contrast, in simulations of inflorescences on which pollen receipt and presentation were segregated so as to minimize interference among flowers, the consistency of movement paths governed mating. In this case, racemes self-pollinated much less than umbels (with panicles being intermediate), and racemes exported much more pollen than umbels and panicles. These effects have diverse consequences for the evolution of inflorescence architecture, flower design, and sexual segregation.

Animals↗
PubMed2004

Convergent evolution of domain architectures (is rare).

MOTIVATION: In this paper, we shall examine the evolution of domain architectures across 62 genomes of known phylogeny including all kingdoms of life. We look in particular at the possibility of convergent evolution, with a view to determining the extent to which the architectures observed in the genomes are due to functional necessity or evolutionary descent. We used domains of known structure, because from this and other information we know their evolutionary relationships. We use a range of methods including phylogenetic grouping, sequence similarity/alignment, mutation rates and comparative genomics to approach this difficult problem from several angles. RESULTS: Although we do not claim an exhaustive analysis, we conclude that between 0.4 and 4% of sequences are involved in convergent evolution of domain architectures, and expect the actual number to be close to the lower bound. We also made two incidental observations, albeit on a small sample: the events leading to convergent evolution appear to be random with no functional or structural preferences, and changes in the number of tandem repeat domains occur more readily than changes which alter the domain composition. CONCLUSION: The principal conclusion is that the observed domain architectures of the sequences in the genomes are driven by evolutionary descent rather than functional necessity. CONTACT: gough@supfam.org.

Conserved Sequence↗